I don't have anything written for File Size but I made a simple little function to return just True/False using Dir():

Public Function fcnFileExists(inFileToTest As String) As Boolean 'This function will test to see if the passed in file exists. 'It will return True if the file exists and False if not. 'Check for file with Dir() and pass back result fcnFileExists = (Dir(inFileToTest) <> "")End Function